Reporter: She has played the awkward girl who hid behind the glasses in the blockbuster, "steel magnolias." But this morning, daryl hannah reveals that shyness on screen wasn't all an act. I'm shy. Reporter: In "people" magazine, hitting newsstands today, the actress says as a child, doctors diagnosed her with autism. And because of the disorder, she has suffered from debilitating shyness most of her life. She tells the magazine, I've never been comfortable being the center of attention. It always freaked me out. Hannah says, as her career took off, she couldn't bring herself to do talk shows or attend movie premieres, saying not because i was above it. But because I was terrified. It's something she has managed better as she's gotten older because she's much more confident. Reporter: As a child, hannah says she rocked incessantly, a common symptom of autism. And says she still does. Doctors recommended she be institutionalized. But says her schoolteacher mother refused. Hannah found comfort in watching old movies. And eventually moved to hollywood, making a splash playing that beautiful, blonde mermaid. Acting is not a surprise career move for a person with autism. The ability it will bring is highly desirable for an individual on the autism spectrum. Reporter: Today at 52, hannah spends much of her time as an environmental activist. She was arrested outside of the white house protesting the keystone pipeline. She tells "people" magazine, i wasted so much time scared, self-conscious and insecure. She may have spent a career in hiding, but not anymore. For "good morning america," see celia vega, abc news, los angeles. It's wonderful she's coming forward like this. I was on a set with her I had a cameo in "hot flashes." Daryl was lovely and so quiet. I can't remember somebody coming out and discussing. So many people. It's great. It is. Working on the sweat -- working up a sweat of the "gma

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